I’m driving the kids home from school. They are whispering to each other about something that happened in the playground.

I can tell from the way the boy occasionally shoots sidelong glances at me that access to this conversation is purely on a need to know basis.

“What are you talking about?” I ask, glancing at them in the rear view mirror.

The eldest, looks up and then away out of the window, shrugging.

“Nothing”, he says.

The four-year-old is less discreet.

“Someone swore in the playground”, she says beaming.

“I didn’t know it was swearing at first, but it definitely was one.”

The eldest sighs and looks at his sister with an air of recrimination, of playground codes broken.

I look back at my daughter and adopt my most serious, yet assuring tone.

“This is probably what Ban-ki Moon sounds like when he talks to his children”, I think.

“Well, what did they say?”

My daughter is looking shifty now, the realisation that she is going to have to say this word-to-end-all-words is sinking in, and she’s not sure how a grown-up will react.

The seven-year-old, now intrigued to see how the situation will play out, is looking more interested.

“It’s OK, I won’t be cross,” I say. “I just need to know. It’s something we might have to tell the school about.”

She looks horrified at the thought.

“I don’t want you to tell the school,” she says. Her face starts to crumple.

“Alright”, I say conspiratorially, “It’ll be just between the three of us.”

“I definitely will tell the school”, I think, changing gear.

She narrows her eyes at me, still unsure.

“Well...what was it,” I coax in my best Ban-ki argot.

She hesitates, takes a deep breath and then shouts it out.

“Shin!”

“What?” I reply, startled.

The boy, eyes twinkling, puts a hand over his mouth, laughing – taking my confusion as a sign that his sister has hit the mark with a truly disgusting word.

“Shin!” the four-year-old shouts again triumphantly.

“Shin! Shin! Shin!”

“Shin!” the boy shouts back. “Shin!”

Then getting into his stride, adds: “Shin face! Shin breath! Shin pad!”

I can sense the children are waiting for my response.

I panic.

“You shouldn’t say shin,” I say. “It is a very, very naughty word. It’s probably one of the worse things you could say.”

We reach the house and the kids rush inside, sprinting up the stairs to their rooms.

Putting the kettle on, I hear them whispering “shin” at each other across the landing. They are squealing with delight.

Over the next week I can’t help but feel guilty that I’ve misled the children.

The thing is I’m not actually against swearing, it’s an important part of the English language. When used well – not just as a lazy replacement for an adjective – swear words can be as relevant, useful and beautiful as any other. After all, these are old words, words that have been loved and worn smooth for our tongues by generations since the Anglo Saxons.

“If swearing was good enough for King Raedwald, it’s good enough for me and it’s good enough for my kids” I think.

I look online and find a paper by psychologists at Keele University. Their research reveals that swearing is actually an important part of humans’ emotional language – it can help us cope with physical pain and serious situations.

“I feel bad about telling the kids shin is a swear word,” I say to my wife. “Do you think we should tell them the truth?”

She looks at me with horror.

“No, they’ll constantly badger us until we tell them what the real swear word is. We’ve just got to ignore it and hope it all goes away.”

Two days later and I am driving the youngest to a birthday party. Navigating a roundabout, a driver pulls out in front of me. I slam on the brakes, hit the horn and swear venomously under my breath.

We pull off again.

I can feel the four-year-old’s eyes boring into the back of my head.

I feel clammy, waiting for the question.

“Daddy...”she begins.

“What did you say about that man?”

I look at her innocent little face in the mirror. It’s like butter wouldn’t melt.

“You called that man a shin.”

A wave of relief passes over me. “Yes, I did,” I say, “It was very naughty of me, but let’s not tell mummy.”